The influence of pressure on the large deformation shear response of a Polyurea

Abstract

A new shear-compression experiment is developed to characterize the influence of hydrostatic pressure on the shear constitutive response of nearly incompressible viscoelastic materials undergoing large deformations. In this design, a uniform torsional shear stress is superposed on a uniform hydrostatic compressive state of stress generated by axially deforming samples confined by a stack of thin steel disks. The new design is effective in applying uniform multiaxial compressive strain while preventing buckling and barreling during inelastic deformation. In addition, it allows for the direct measurement of the stress and strain fields during the deformation history. The new shear-compression setup is developed to aid in characterizing the influence of pressure or negative dilatation on the shear constitutive response of viscoelastic materials in general and Polyurea in particular. Experimental results obtained with this technique illustrate the significant increase in the shear stiffness of polyurea under moderate to high hydrostatic pressures. ©2010 Society for Experimental Mechanics Inc.